Tobacco moisture determining apparatus including a conveying means having an elongated duct with an overflow channel



May 16, 1967 A. ESENWEIN 3,

TOBACCO MOISTURE DETERMINING APPARATUS INCLUDINGA CONVEYING MEANS HAVING AN ELONGATED DUCT WITH AN OVERFLOW CHANNEL Filed May '7, 1962 Jn van for: I? Jurt United States Patent 3,320,523 TOBACCO MOISTURE DETERMINING APPARA- TUS INCLUDING A CONVEYING MEANS HAV- ING AN ELGNGATED DUCT WITH AN OVER- FLOW CHANNEL Albert Esenwein, Hamburg-Lohbrugge, Germany, assignor to Hauni Werke, Korber & C0., K.G., Hamburg- Bergedorf, Germany Filed May 7, 1962, Ser. No. 192,834 Claims priority, application Germany, May 10, 1961, H 42,552 9 Claims. (Cl. 324-61) The present invention relates to improvements in apparatus for determining the moisture content of fibrous and like particulate materials, and more particularly to an apparatus which is especially suited for determining the moisture content of tobacco.

An important object of the invention is to provide an apparatus for determining the moisture content of a stream of tobacco or a similar particulate material which is constructed and assembled in such a way that it can continuously determine the moisture content with an accuracy substantially exceeding the accuracy of conventional apparatus of which I am aware at this time, and which can determine the moisture content irrespective of fluctuations in the rate at which the material flows.

Another object of the invention is to provide an apparatus of the just outlined characteristics which determines the moisture content of tobacco or a similar particulate material by measuring the dielectric constant of a stream of particles and which is capable of conveying a stream of material in such a way that the cross sectional area of the stream at the point of measurement is always the same so that the measurements accurately reflect the moisture content of the conveyed material.

A further object of the invention is to provide an apparatus of the above outlined characteristics which insures that the density of the stream of material at the point or in the zone in which the measurement is made remains unchanged even through the rate at which the material is being fed may fluctuate within a rather wide range.

With the above objects in view, the invention resides in the provision of an apparatus which comprises means for conveying a stream of tobacco or like fibrous or other particulate material in a predetermined path, this conveying means defining a measuring duct and at least one overflow channel which is adjacent to and whose bottom zone is located at a level below the upper zone of the measuring duct, a feed for admitting a stream of material into the measuring duct at a rate suflicient to at least fill this duct so that any particles in excess of those necessary to fill the duct may spill into the overflow channel, and means comprising capacitor means located in the measuring duct downstream of the material admitting means for determining the dielectric constant and hence the moisture content of the material passing through the measuring duct.

In accordance with a feature of my invention, the measuring duct may be provided between a pair of overflow channels so that excess material may spill from both sides of the duct, and the capacitor means may comprise a first capacitor which is located in the lowermost zone of the measuring duct as Well as two additional capacitors which are disposed at the opposite sides of and which are arranged symmetrically with respect to the first capacitor. The first capacitor is connected in series with a source of electrical energy and with a potentiometer which indicates whether or not any current flows from the first capacitor to the additional capacitors.

The novel features which are considered ,as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a top plan view of a novel tobaccoadvancing trough which forms part of an apparatus for determining the moisture content of tobacco and like fibrous materials;

FIG. 2 is a greatly enlarged transverse section as seen in the direction of arrows from the line IIII of FIG. 1;

FIG. 3 is a side elevational view of the entire apparatus, further showing a conveyor which delivers tobacco into and an elevator which receives tobacco from the trough; and

FIG. 4 is a schematic view of a modified electric circuit which may be utilized in the apparatus of FIGS. 1 to 3.

Referring now in greater detail to the illustrated embodiments, and first to FIGS. 1 to 3, there is shown an apparatus for determining the moisture content of tobacco and which comprises a conveying means in the form of an elongated substantially U-shaped receptacle or trough 1 which causes a stream T of tobacco to advance in an elongated path in a direction from the left to the right, as viewed in FIGS. 1 and 3. The trough 1 comprises a pair of spaced upright side walls 2c, 2c and a composite bottom wall including two spaced substantially horizontal outer bottom wall portions 2, 2 which extend inwardly from the lower ends of the side Walls 2c, 2c, respectively; two intermediate bottom wall portions 2a, 2a which extend upwardly from the inner ends of the bottom wall portions 2, 2; and two mutually inclined central bottom wall portions 2b, 2b which extend downwardly from the upper ends of the bottom wall portions 2a, 2a and which define between themselves an upwardly open substantially V-shaped measuring duct 3. Since the tobacco particles are fed into the measuring duct 3 and since the upper zone of this duct extends to a level above the outer bottom wall portions 2, 2', the duct 3 is automatically filled with tobacco before any tobacco can spill into one or both overflow channels 10, 10' which are outwardly adjacent to the intermediate bottom wall portions 2a, 2a. In other words, the bottom zones of the channels 10, 10' are located at a level below the upper zone of the duct 3. The trough 1 may be agitated by a vibrator or shaker 11 which is shown in FIG. 3 and which insures that the stream of tobacco particles contained in the duct 3 levels otf before reaching the device which actually determines its moisture content and which, in the embodiment of FIGS. 1 to 3, is located close to the discharge end of the trough 1. This device comprises a pair of plate-like capacitors 4-, 4 which are accommodated in the duct 3 and which are respectively supported by the central bottom wall portions 212, 2b, and a third plate-like capacitor 4a which is mounted in the lowermost zone of the duct 3 intermediate the capacitors 4, 4'. The capacitor 4a is connected in series with a. battery 12 or another source of electrical energy, and the electric circuit further comprises a potentiometer 13 which is calibrated to provide readings indicative of the dielectric constant and hence of the equalized moisture content of the tobacco stream advancing through the measuring duct 3.

FIG. 3 shows that the intake end of the trough 1 is located below the discharge end of a feed here shown as a belt conveyer 5 which delivers a stream of tobacco particles into the duct 3, and the discharge end of the trough 1 delivers tobacco into a hopper 14 provided above the endless travelling element 15 of an elevator J 7 which advances tobacco into a chute 9 whence the material descends onto the grating (not shown) of a drying apparatus which may assume the form of a conventional roaster. The vibrator 11 is mounted on a table 16 which carries pairwise arranged links 17, the latter articulately connected to the trough 1 and rockable in directions indicated by double arrows when the motor 18 of the vibrator drives a disk 19 whose eccentrin pin reciprocates a shaker arm 20 secured to the underside of the trough 1. The action of the vibrator 11 is preferably selected in such a way that tobacco contained in the trough 1 advances at the same rate of speed at which the conveyor delivers tobacco into the duct 3.

The apparatus of my invention further comprises a temperature-responsive measuring device 8 which is lo cated downstream of the capacitors 4, 4, 4a and which transmits impulses to a control device 21, the latter serving as a means for regulating the action of the roaster in dependency on the moisture content and on the temperature of tobacco discharged by the trough 1. As shown, the control device 21 also receives impulses from the potentiometer 13.

It is assumed that the trough 1 consists of metallic material and that the capacitors 4, 4', 4a are insulated from the central bottom wall portions 2b, 2b.

The apparatus of FIGS. 1 to 3 operates as follows:

The conveyer 5 admits a stream of tobacco particles at such a rate that the tobacco particles fill the duct 3 and overflow by descending into the channels 10, while simultaneously advancing in the elongated path defined by the trough 1, i.e. in a direction indicated in FIG. 3 by the arrow 22. The rate at which the conveyer 5 delivers tobacco is selected in such a way that the overflow channels 10, 10' are not completely filled even though the duct 3 is filled all the way up to the upper ends of the central bottom wall portions 217, 2b to contain an equalized tobacco stream of constant cross-section. Since the trough 1 vibrates and thereby advances the tobacco particles toward the hopper 14, that is, away from the conveyer 5, the stream of tobacco particles admitted to the duct 3 fills this duct and is levelled ofl before reaching the capacitors so that the potential difference which is built up symmetrically between the capacitors 4, 4' (which are connected in parallel) and the capacitor 4a (which is connected to the source 12) reflects the dielectric constant and hence the moisture content of the tobacco stream flowing in the duct 3 with utmost accuracy. The device 8 measures the temperature of the tobacco stream before the tobacco particles passing through the duct 3 are discharged into the hopper 14. The potentiometer 13 and the temperature-responsive measuring device 8 transmits impulses to the control device 21 which latter transmits impulses to an amplifier (not shown) so that the amplifier may adjust a suitable mechanism which regulates the admission of a heating medium (e.g. hot air) to the roaster. The manner in which the device 21 modifies impulses received from the potentiometer 13 in dependency on impulses received from the device 8 to thereupon regulate admission of a heating medium to the roaster is well known in the art and forms no part of the present invention.

A very important advantage of the measuring duct 3 is that, merely, by regulating the rate at which tobacco is admitted to the trough 1 and/or by regulating the action of the vibrator 11, the cross-sectional area of the equalized tobacco stream T passing above the capacitors 4, 4-, 4a is always the same. This feature diflerentiates the improved apparatus from certain known apparatus in which the measuring duct extends to a level below the bottom level of the overflow channels and in which tobacco particles will pile up in the measuring duct as soon as the trough receives more tobacco than necessary to fill the measuring duct. Owing to the fact that at least the upper zone of the measuring duct 3 extends to a level above the bottom level of the overflow channels 10, 10, excess tobacco will automatically spill over and descend into the overflow channels before the stream T of tobacco particles passing along the measuring duct reaches the capacitors. Consequently, the dielectric constant of the tobacco stream pass-ing above the capacitors reflects truly the moisture content of tobacco and enables the improved apparatus to measure the moisture content with an accuracy of up to 99.99 percent. The accuracy of measurements is improved by the novel arrangement of capacitors which produce a symmetric potential because the capacitor 4a is located in the lowermost zone of the duct 3 midway between the capacitors 4-, 4'. Of course, the stream of tobacco particles is a quasi dielectric since its conductivity varies in dependency on its moisture content, and this particular characteristic is utilized for determining the moisture content of tobacco. As a rule, the trough 1 is vibrated in such a way that the material contained in the duct 3 and channels 10, 10' advances at a constant speed.

It will be readily understood that one of the overflow channels 16), 10 may be omitted so that, for example, the side wall 2c may extend upwardly from the upper end of the central bottom wall portion 2b and that the channel 10 then receives all tobacco particles which spill over in the measuring duct 3. This modification of my invention is so obvious that it can be understood by men skilled in the art without additional illustrations.

Since the vibrating trough 1 loosens up the particles in the tobacco stream admitted by the conveyer 5, and since the trough causes excess tobacco to spill into the channels 10, 10, the density of the tobacco stream passing above the capacitors remains unchanged regardless of the rate at which the conveyor 5 feeds tobacco to the trough, as long as the rate of feed is sufflcient to at least fill the duct 3 but less than is necessary to fill the channels 10, 10' up to the level of the upper zone of the duct 3, i.e. flush with the upper ends of the bottom wall portions 2a, 2a and 2b, 2b.

FIG. 4 shows a portion of a slightly modified apparatus in which the capacitors 4, 4 and the potentiometer 13 are grounded so that the ground constitutes a common return line for the electric current. This type of electric circuit may be utilized if only the capacitor 4a is insulated from the trough 1 and if the trough constitutes a connection between the capacitors 4, 4 and the ground.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of .prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in a predetermined path, said conveying means defining an elongated duct and at least one overflow channel positioned to receive the material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate sufficient to at least fill said duct but less than required to fill said duct and said overflow channel so that any particles in excess of those necessary for filling the duct may overflow into said channel whereby the material remaining in the thus filled duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, comprising capacitor means including plate means located in said duct downstream of said feed.

2. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in a predetermined path, said conveying means defining an elongated duct and at least one overflow channel positioned to receive the material 'which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate sufiicient to at least fill said duct but less than necessary to fill said duct and said channel so that any particles in excess of those necessary for filling the duct overflow into said channel whereby the material remaining in the thus filled duct forms an equalized stream; means for determining the dielectric constant of the equalized stream in said duct comprising capacitor means including plate means located in said duct downstream of said feed; and transporting means arranged to receive the equalized stream from said duct downstream of said capacitor means and to receive any such material which spills into said channel.

3. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in an elongated path, said conveying means comprising a receptacle defining an elongated duct and at least one elongated overflow channel positioned to receive the material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at .a rate sufiicient to at least fill said duct but less than required to fill said overflow channel and said duct; means for vibrating said receptacle and for thereby advancing the material along said duct in a direction away from said feed so that any particles in excess of those necessary to fill said duct overflow into said channel whereby the material remaining in the thus filled duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, comprising capacitor means including plate means located in said duct downstream of said feed.

4. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in a predetermined path, said conveying means defining an upwardly open substantially V-shaped elongated duct and at least one overflow channel positioned to receive the material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate suflicient to at least fill said duct but less than required to fill said duct and said overflow channel so that any particles in excess of those necessary for filling the duct overflow into said channel whereby the material remaining in the thus filled duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, comprising capacitor means including plate means located in said duct downstream of said feed.

5. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in a predetermined path, said conveying means defining a pair of spaced elongated overflow channels and an elongated duct disposed intermediate said channels, said channels being positioned to receive material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate suflicient to at least fill said duct but less than required to fill said channels and said duct so that any particles in excess of those necessary for filling the duct overflow into said channels whereby the material remaining in the thus filled duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, comprising capacitor means including plate means located in said duct downstream of said feed.

6. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in an elongated path, said conveying means comprising a receptacle defining an elongated duct and at least one elongated overflow channel positioned to receive the material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate suflicient to at least fill said duct but less than required to fill said channel and said duct; means for vibrating said receptacle and for thereby advancing the material along said duct in a direction away from said feed whereby any particles in excess of those necessary for filling said duct overflow into said channel so that the material remaining in said duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, comprising capacitor means including a first plate located in the bottom portion of said duct and a pair of additional plates located at the opposite sides of said first plate.

7. In an apparatus for determining the moisture content of tobacco and like particulate materials, in combination, means for conveying the material in an elongated path, said conveying means comprising a receptacle defining an upwardly open substantially V-shaped elongated duct and at least one overflow channel immediately adja cent to one side of said duct to receive the material which overflows laterally upon filling of said duct; a feed for admitting a stream of material into said duct at a rate suflicient to at least fill said duct but less than required to fill said channel and said duct; means for vibrating said receptacle and for thereby advancing the material along said duct in a direction away from said feed whereby any particles in excess of those necessary to fill said duct overflow into said channel and the material remaining in said duct forms an equalized stream; and means for determining the dielectric constant of the equalized stream in said duct, including capacitor means comprising a first plate located in the bottom portion of said duct and a pair of additional plates located at the opposite sides of and arranged symmetrically with respect to said first plate.

8. A combination as set forth in claim 7, wherein said additional plates are connected in parallel, and further comprising a source of electrical energy connected in series with said first plate.

9. A combination as set forth in claim 7, wherein each of said plates is grounded, and further comprising a source of electrical energy and a potentiometer connected in series between said first plate and the ground.

References Cited by the Examiner UNITED STATES PATENTS 2,164,676 7/1939 Appleyard et al 198-220 2,266,114 12/1941 Bartlett 324-61 3,046,479 7/1962 Mead et al 32461 FOREIGN PATENTS 827,004 1/1960 Great Britain. 827,708 2/1960 Great Britain.

WALTER L. CARLSON, Primary Examiner.

J. P. OBRIEN, E. E. KUBASIEWICZ,

Assistant Examiners. 

1. IN AN APPARATUS FOR DETERMINING THE MOISTURE CONTENT OF TOBACCO AND LIKE PARTICULATE MATERIALS, IN COMBINATION, MEANS FOR CONVEYING THE MATERIAL IN A PREDETERMINED PATH, SAID CONVEYING MEANS DEFINING AN ELONGATED DUCT AND AT LEAST ONE OVERFLOWS CHANNEL POSITIONED TO RECEIVE THE MATERIAL WHICH OVERFLOWS LATERALLY UPON FILLING OF SAID DUCT; A FEED FOR ADMITTING A STREAM OF MATERIAL INTO SAID DUCT AT A RATE SUFFICIENT TO AT LEAST FILL SAID DUCT BUT LESS THAN REQUIRED TO FILL SAID DUCT AND SAID OVERFLOW CHANNEL SO THAT ANY PARTICLES IN EXCESS OF THOSE NECESSARY FOR FILLING THE DUCT MAY OVERFLOW INTO SAID CHANNEL WHEREBY THE MATERIAL REMAINING IN THE THUS FILLED DUCT FORMS AN EQUALIZED STREAM; AND MEANS FOR DETERMINING THE DIELECTRIC CONSTANT OF THE EQUALIZED STREAM IN SAID DUCT, COMPRISING CAPACITOR MEANS INCLUDING PLATE MEANS LOCATED IN SAID DUCT DOWNSTREAM OF SAID FEED. 